1. Field of the Invention
The present invention relates to a method for fabricating a field emission display with a carbon-based emitter.
2. Description of the Related Art
A quality of a field emission display using a cold-cathode as an electron emission source depends on a characteristic of an emitter which is an electron emission layer.
Conventionally, such an emitter is formed in a tip-shaped spindt type made of Mo-based metal. Such a tip-shape spindt type emitter is disclosed in the U.S. Pat. No. 3,789,471.
However, to fabricate a field emission display having such a tip-shaped emitter, a series of semiconductor manufacturing processes such as photolithography and etching processes for forming holes for fixing the emitter and a vapor deposition process for depositing Mo to form the metal tip. However, these processes are time-consuming and costly.
Accordingly, techniques for forming a planar emitter have been developed to simplify the manufacturing process while allowing the emitter to emit electrons under a relatively low voltage (10–50V) driving condition.
As a material for forming the planar emitter, well known is a carbon-based material such as graphite, diamond and carbon nanotube. Particularly, the carbon nanotube is expected as the most ideal material for the planar emitter as it effectively emits electrons under a relatively lower driving voltage.
An electric field emission display with such a carbon nanotube emitter is disclosed, for example, in the U.S. Pat. Nos. 6,062,931 and 6,097,138.
In the patents, the carbon nanotube emitter is formed through a PCVD (Plasma Chemical Vapor Deposition) process, a coating process, a printing process and the like.
However, when the emitter is formed using the carbon-based material through a series of processes, the surface property of the planar emitter easily deteriorates, because the carbon-based material has a high bonding energy with other materials used in such processes.
For example, a photolithography process should be performed to form an electrode (gate and focusing electrodes) for emitting electric field on the emitter. A photoresist used for the photolithography process remains on the emitter surface, deteriorating the electric field emission characteristic. Etching solution used for patterning the electrode also deteriorates the emitter performance.
In addition, when the emitter is heat-treated for baking, the carbon contained in the emitter is burned as it reacts with oxygen (see FIG. 4).
As described above, when the emitter is formed of a carbon-based material, a variety of problems are encountered.